how tomcat works-02

Request

Response

RequestFacade

ResponseFacade

StaticSourceProcessor

ServletProcessor

HttpServer

Constants

---

Request.java

package qhf02.pyrmont;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.UnsupportedEncodingException;
import java.util.Enumeration;
import java.util.Locale;
import java.util.Map;

import javax.servlet.AsyncContext;
import javax.servlet.DispatcherType;
import javax.servlet.RequestDispatcher;
import javax.servlet.ServletContext;
import javax.servlet.ServletInputStream;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;

public class Request implements ServletRequest {
	
	private InputStream input;
	private String uri;
	
	public Request() {
		super();
	}
	
	public Request(InputStream input) {
		this.input = input;
	}
	
	public String getUri() {
		return uri;
	}

	public void parse() {
		
		StringBuffer request = new StringBuffer(2048);
		
		int len;
		byte[] buffer = new byte[2048];
		try {
			len = input.read(buffer);
		} catch (IOException e) {
			e.printStackTrace();
			len = -1;
		}
		
		for (int j = 0; j < len; j++) {
			request.append((char) buffer[j]);
		}
		
		System.out.println(request.toString());
		
		uri = parseUri(request.toString());
	}

	/**
	 * 	第一行的第一個空格和第二個空格之間就是uri
	 * 	比如：GET /index.html HTTP/1.1
	 **/
	private String parseUri(String requestString) {
		int index1, index2;
		index1 = requestString.indexOf(' ');
		if(index1 != -1) {
			index2 = requestString.indexOf(' ', index1 + 1);
			if(index2 > index1) {
				return requestString.substring(index1 + 1, index2);
			}
		}
		return null;
	}

	@Override
	public AsyncContext getAsyncContext() {
		// TODO Auto-generated method stub
		return null;
	}

	@Override
	//....實現父類接口的方法
}

Response.java

package qhf02.pyrmont;

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.util.Locale;

import javax.servlet.ServletOutputStream;
import javax.servlet.ServletResponse;

public class Response implements ServletResponse {

	private static final int BUFFER_SIZE = 1024;
	Request request;
	OutputStream output;
	PrintWriter writer;
	
	public Response() {
		super();
	}

	public Response(OutputStream output) {
		this.output = output;
	}

	public void setRequest(Request request) {
		this.request = request;
	}

	public void sendStaticResource() throws IOException {
		byte[] bytes = new byte[BUFFER_SIZE];
		FileInputStream fis = null;
		
		try {
			File file = new File(HttpServer1.WEB_ROOT, request.getUri());
			if (file.exists()) {
				fis = new FileInputStream(file);

				int ch = fis.read(bytes, 0, BUFFER_SIZE);

				while (ch != -1) {
					output.write(bytes, 0, ch);
					ch = fis.read(bytes, 0, BUFFER_SIZE);
				}
			} else {
				// file not found
				String errorMessage = "HTTP/1.1 404 File Not Found\r\n"
						+ "Content-Type: text/html\r\n"
						+ "Content-Length: 23\r\n" 
						+ "\r\n"
						+ "<h1>File Not Found</h1>";

				output.write(errorMessage.getBytes());
			}

		} catch (Exception e) {
			System.out.println(e.toString());
		} finally {
			if (fis != null) {
				fis.close();
			}
		}
	}
	public static void main(String[] args) {
		System.out.println(System.getProperty("user.dir") + File.separator + "webroot");
	}

	@Override
	public PrintWriter getWriter() throws IOException {
		writer = new PrintWriter(output, true);//println時自動刷新
		return writer;
	}
    
    //...實現父類接口的方法
}

RequestFacade

package qhf02.pyrmont;

import java.io.IOException;
import java.io.BufferedReader;
import java.io.UnsupportedEncodingException;
import java.util.Enumeration;
import java.util.Locale;
import java.util.Map;

import javax.servlet.AsyncContext;
import javax.servlet.DispatcherType;
import javax.servlet.RequestDispatcher;
import javax.servlet.ServletContext;
import javax.servlet.ServletInputStream;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;

public class RequestFacade implements ServletRequest {

  private ServletRequest request = null;

  public RequestFacade(Request request) {
    this.request = request;
  }

  /* implementation of the ServletRequest*/
  //實現父類接口的方法，return則調用關於request的方法

}

ResponseFacade

package qhf02.pyrmont;

import java.io.IOException;
import java.io.PrintWriter;
import java.util.Locale;
import javax.servlet.ServletResponse;
import javax.servlet.ServletOutputStream;

public class ResponseFacade implements ServletResponse {

  private ServletResponse response;
  public ResponseFacade(Response response) {
    this.response = response;
  }

  //實現父類接口的方法，return關於response的相關方法

}

StaticSourceProcessor

package qhf02.pyrmont;

import java.io.IOException;

public class StaticResourceProcessor {
	
	public void process(Request request, Response response) {
		try {
			response.sendStaticResource();
		} catch (IOException e) {
			e.printStackTrace();
		}
	}
}

ServletProcessor2

package qhf02.pyrmont;

import java.io.File;
import java.io.IOException;
import java.net.URL;
import java.net.URLClassLoader;
import java.net.URLStreamHandler;

import javax.servlet.Servlet;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;

public class ServletProcessor2 {

	public void process(Request request, Response response) {
		String uri = request.getUri();
		String servletName = uri.substring(uri.lastIndexOf("/") + 1);
		
		URLClassLoader loader = null;	
		try {
			URL[] urls = new URL[1];
			File classPath = new File(Constants.WEB_ROOT);
			
			String repository = (new URL("file", null, classPath.getCanonicalPath() + File.separator)).toString();
			URLStreamHandler streamHandler = null;
			
			urls[0] = new URL(null, repository, streamHandler);
			loader = new URLClassLoader(urls);
			
		} catch (IOException e) {
			System.out.println(e.toString());
		}
		
		Class<?> myClass = null;
		try {
			myClass = loader.loadClass(servletName);
		} catch (Exception e) {
			System.out.println(e.toString());
		}
		
		Servlet servlet = null;
		RequestFacade requestFacade = new RequestFacade(request);
		ResponseFacade responseFacade = new ResponseFacade(response);
		try {
			servlet = (Servlet) myClass.newInstance();
			servlet.service((ServletRequest)requestFacade, (ServletResponse)responseFacade);
		} catch (Exception e) {
			System.out.println(e.toString());
		} catch (Throwable e) {
			System.out.println(e.toString());
		}
	}
	
}

HttpServer2

public class HttpServer2 {
	public static final String WEB_ROOT = System.getProperty("user.dir") + File.separator + "webroot";
	
	private static final String SHUTDOWN_COMMAND = "/SHUTDOWN";
	
	private boolean shutdown = false;
	
	public static void main(String[] args) {
		HttpServer2 server = new HttpServer2();
		server.await();
	}

	private void await() {
		ServerSocket serverSocket = null;
		int port = 8080;
		try {
			serverSocket = new ServerSocket(port, 1, InetAddress.getByName("127.0.0.1"));
		} catch (IOException e) {
			e.printStackTrace();
			System.exit(1);
		}
		
		while (!shutdown) {
			Socket socket = null;
			InputStream input = null;
			OutputStream output = null;
			
			try {
				//1.服務器開機，等待連接，直到連接了執行這下面23後關socket，下次循環再連接
				socket = serverSocket.accept();
				
				input = socket.getInputStream();
				output = socket.getOutputStream();
				
				//2.解析請求
				Request request = new Request(input);
				request.parse();
				
				//3.迴應設置對應的請求，發送靜態源
				Response response = new Response(output);
				response.setRequest(request);
				
				if(request.getUri().startsWith("/servlet/")) {
					ServletProcessor2 processor = new ServletProcessor2();
					processor.process(request, response);
				} else {
					StaticResourceProcessor processor = new StaticResourceProcessor();
					processor.process(request, response);//其實是簡單封裝了response.sendStaticResource();
				}
				
				
				
				//4.關socket
				socket.close();
				
				//5.檢查請求中的uri 中是否是shutdown 命令，如是則shutdown 爲true 會退出循環
				shutdown = request.getUri().equals(SHUTDOWN_COMMAND);
				
			} catch (Exception e) {
				e.printStackTrace();
				continue;//錯誤繼續循環
			}
		}
	}
}

Constants

public class Constants {
	public static final String WEB_ROOT = System.getProperty("user.dir") + File.separator + "webroot";

	public static void main(String[] args) {
		System.out.println(WEB_ROOT);
	}
}